Having improved my Thing-O-Matic mechanics about as much as can be cough reasonably expected, the stepper motors driving the X and Y axes still seem to be running at about the limit of their ability. It’s time for some doodling on that subject; let’s start by collecting all the data in one spot.
The X and Y motors are, as far as I can tell, inherited directly from the MBI Cupcake CNC. They seem to be Kysan 42BYG034-4.78 (aka SKU 1123029) described on that Kysan store product page as:
- 35 OHM
- 3/16 SHAFT
- 8 DEGREE (error: should be 1.8°)
- 2.3KG-CM MAX
The Kysan Electronics product page has more data, including a torque curve:
Note that, unlike most NEMA 17 steppers, this puppy does not have a 5 mm shaft (unlike the electrically identical Kysan 42BYG034, which does). A 5 mm pulley is a poor fit on a 4.78 mm shaft and, conversely, you must drill / bore MBI pulleys to fit other steppers.
If one was to buy a replacement pulley with a 5 mm bore, the A 6D51M018DF0605 from SDP might do the trick. Or you could apply a 0.199 inch (#8) drill to the bore and save twenty bucks.
The Z stepper has an integrated 4-start leadscrew, so it’s not suitable for a drop-in replacement without some Quality Shop Time. That comment leads to that Kysan store product page for Kysan 17HD011-200N (aka SKU 1040104), with this data:
- 200MM LEAD SCREW
- 1.8 DEGREE
- 30 OHM
- 260mN.m HOLDING TORQUE
The Kysan Electronics product page has more data (although the proffered PDF datasheet is empty), including a low-res torque curve:
The Z axis motor on my TOM is labeled “PN 1040103”, which leads to that Kysan Electronics product page for 17HD-8X150MM0.4A, with just a mechanical drawing. The electrical properties seem identical.
The MK6 Extruder (MBI assembly and setup doc there) stepper motor evidently arrives without ID, but that comment suggests it’s an Anaheim Automation 17Y402S-LW4-01 or something similar. That discussion indicates the motor has a 5 mm shaft, not the 6 mm that would match the standard MK5/MK6 filament drive gear, and that MBI did another custom order.
Following various links leads us to the data table there, wherein we find:
- Coil resistance = 12 Ω
- Coil inductance = 29 mH
- Rated current = 850 mA
- Rated voltage = 10.2 V
The torque curve:
One observation: these motors have extremely high winding resistance. That makes them suitable for low-speed H-bridge drivers without current control, not contemporary stepper drivers with chopper current control.